[Click] How to reference Method Interfaces?

[Javier Sánchez Recacha]

2) Acces to the capacity variable of the queue element.

click script:

RatedSource(\<0800>) -> q::Queue -> MyPrint(q) -> Discard();

MyPrint.hh

...
  private:
  Element *_e;
...

MyPrint.cc

#include <click/config.h>
#include "myprint.hh"
#include <click/confparse.hh>
#include <click/error.hh>

// to read a variable from an element you need 2 conditions

// 1) Element has to have the cast() method, if it doesn't,
//    is easy to implement, f.e. look at click/standard/storage.hh
// 2) Element has to have a public function that returns the value you want
//
// p.e. Queues has the function cast() (inherited from simplequeue.hh )
// that returns the element type Storage and the function capacity() 
(inherited from
// storage.hh) that returns the capacity value
#include <click/standard/storage.hh>

CLICK_DECLS

MyPrint::MyPrint()
{
}

MyPrint::~MyPrint()
{
}

int
MyPrint::configure(Vector<String> &conf, ErrorHandler *errh)
{
  Element *e;
  if (cp_va_kparse(conf, this, errh,
        // here we take the pointer to the element
             "ELEMENT", cpkP+cpkM, cpElement, &e,
             cpEnd) < 0)
  return -1;
  _e = e;
  return 0;
}

Packet *
MyPrint::simple_action(Packet *p)
{
//here the general element _e is read as storage element s.

  if (Storage *s = (Storage *)_e->cast("Storage")){
  click_chatter ("Element %s capacity: %d",_e->name().c_str(), 
s->capacity());
  }
 
  return p;
}

CLICK_ENDDECLS
EXPORT_ELEMENT(MyPrint)
ELEMENT_MT_SAFE(MyPrint)